CSCI-1200 Computer Science II — Fall 2007
Lab 13 — Priority Queues and Binary Heaps
In this lab, you will use binary heaps to implement the priority queue container, as discussed in Lectures 21
and 22. Having these notes available while you are working on this lab will make it substantially easier.
Start by downloading the files, and then turn off all network connections:
http://www.cs.rpi.edu/academics/courses/fall07/cs2/labs/13_priority_queues/priority_queue.h
http://www.cs.rpi.edu/academics/courses/fall07/cs2/labs/13_priority_queues/test_pq.cpp
The code provided in these files is straightforward. test_pq.cpp is a driver and test program, while
priority_queue.h is a skeleton implementation. Please take a careful look. You will complete the
implementation and add to the main program in lab. In your implementation, be careful of subtracting 1
from an unsigned int whose value is 0; it is not -1!
Checkpoint 1
Implement and test the push (a.k.a. insert) and the check_heap functions. Recall that push depends
on the percolate_down functionality. check_heap, which works either with the heap member variable or
with a vector provided from the outside, determines if the vector is properly a heap, meaning that each
value is less than or equal to the values of both of its children (if they exist).
To complete this checkpoint: Show a TA your debugged implementation and discuss the running time
of both insert and check_heap.
Checkpoint 2
Implement and test the pop (a.k.a. delete_min) function and the constructor that builds a valid heap
from a vector of values that is in no particular order. Both of these depend on proper implementation of
the percolate_down function.
To complete this checkpoint: Show a TA these additions and the test output.
